Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Beyond the annotations, the description discloses important runtime behaviors: a window matching nobody returns 422 and is not charged, requests before the archive's first date are only partially covered, and each call costs $0.01 USDC on success. It also explains the attribution ranking logic, giving the agent a clear model of what the tool does and what happens on edge cases.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is dense but well-organized: the core purpose comes first, followed by attribution logic, then failure behavior and cost. Every sentence adds distinct information, and there is no filler or repetition of schema details.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The description covers the tool's purpose, row-level attribution meaning, failure modes, pricing, and coverage limits, which is substantial for a read-only tool with only two optional parameters. It does not enumerate every possible row field, but the absence of an output schema is partially mitigated by the explicit statement that each row indicates which attribution it carries.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the parameters limit and since are already fully documented in the schema. The description reinforces the meaning of 'since' by framing it as services first listed after a given date, but it does not add materially new parameter-level meaning beyond the schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly identifies the resource (x402 services first listed since a date) and the specific lens: early-traction evidence from observed inflow. It further distinguishes itself by explaining how attributed entrants rank first and that each row indicates which attribution signal it carries, separating it from sibling trend and ranking tools.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description gives a clear use context: discovering x402 services first listed since a date, with attribution and inflow evidence. It does not explicitly name alternatives or state when to prefer another sibling tool, but the focus on newly listed entrants is specific enough for an agent to select it appropriately.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.